you cant install any mods that you want it wont work if u want the water shaders mod use it in vanilla not tekkit i tried optifine and it wouldnt work for me. i would recommend to tell the tekkit people that they could add the shaders mod but it also might come out in an update
from
miner0149
i would also recommend windows 7 because some thing REQUIRE window 7 not windows XP and i had my antivirus running and it worked fine for me so tell your bro to try to get a windows 7 (not windows 8 my friends minecraft wont work with windows 8) i would recommend that he should get a Dell Insparon